bristunt

Hey fellas, looking for some thoughts.

My wifes superhawk is surging at cruising throttle.
Idle is fine, and acceleration is fine.
Have checked:
Throttle position sensor good
Carbies balanced & bowls drained
Plugs changed just in case
Battery good
Reg/rec good
No vacuume leaks
No jetting changes since running good
Fresh fuel

Any thoughts

mikstr

surging is typically related to a lean condition. How does it run at higher engine speed? A torn diaphragm in the petcock can also cause fuel starvation and create a lean condition (had it happen to me a couple times)

bristunt

I've had a torn petcock diaphram before and it starved for fuel at full noise. This is rich if anything.
It's strange, good one ride, then a month later **** from startup. Even in neutral holding rpm anywhere above idle it is surging.

smokinjoe73

I would more suspect torn carb diaphragm or carb boots not sealed tightly. Carb boot tears are tricky to find to look closely. Reseat the carbs themselves an smear a bit of Vaseline around the mating surface to help.

As it happens carefully pull the choke a bit to see what that does. It should change it somewhat.

smokinjoe73

More likely clogged carb jets. Take this time to install filters in the fuel lines. I would drain the fuel and start fresh when you clean the carbs or more gunk will simply reclog in like 2 blocks.

sjscicluna

Watching this tentatively.

smokinjoe73

tentatively?

Like you can take or leave the outcome?